Water usage and nuclear power plants April 23, 2010

Water usage and nuclear power plants is little known in the U.S., even in areas where water is at a premium such as in the semi-arid western states, where most of the fresh water is consumed in this country. Here are the facts:

About 80% is used for irrigation and much of that is for golf courses, lawns, parks, recreation fields, swimming pools and commercial property beautification. 2 billion gallons per day is used on golf courses alone.

Approximately 10% is used for industry and business.

About 7% is used for household use including some irrigation.

The remainder, around 3.0% is used for thermal power plants. Nuclear, coal, combined cycle gas, CSP solar and geothermal are thermal plants. Coal plants are by far the largest user, followed by nuclear plants, and finally combined cycle gas plants in order of power production.

Figures from the above graph are very similar for Idaho except only about .01% of the fresh water is used for thermal power plants.

Note:
It is critical to point out just how much water leaves southern Idaho on an annual basis without ever being used. In fact, 7,900,000 acre feet of water leaves the state every year via the Snake River, which has the Payette River as one of its tributaries.

A proposed nuclear power plant in Payette County would use less than 1% of this water.

(Source: SPF Water Engineering)

What sources of electricity require the most water?

There are 2400 hydroelectric plants in the United States that require the largest amount of water than any other power producer. However, hydro plants only produce 7% of the nation’s electricity and around 40% in Idaho, which is decreasing according to the Athena report. (http://www.harvestcleanenergy.org/IdahoEnergy/IdahoEnergyFuture_PR.pdf) While there is some evaporation behind the dams, much of the water is held for production of often small amounts of power instead of flood control even when the water is needed in semi-arid climates for crop irrigation and industry. There are no emissions with hydro, however, these plants negatively impact the environment in a variety of ways including fish passage and silting.

There are 600 coal plants in the U.S., which require more water than any other thermal power source due to the large number of units. Coal produces 50% of the nation’s electricity, but they have the worst emissions of all power sources. Many of these emissions contain mercury, sulfur and CO2.

There are 104 nuclear plants in the U.S. which use less water with fewer units than coal. Nuclear power plants produce 20% of the nation’s electricity and 70% of all emission-free electricity.

Combine-cycle gas plants use the least amount of water of all the major power sources because they are the smallest power contributor. However, these plants are rapidly growing in number and emit a large amount of CO2, although those emissions are about half the amount of an equivalent size coal plant.

Geothermal plants produce less than 1% of the nation’s power and use water much like any equivalent size thermal plant. However, many of these plants have to inject water into the earth, which requires even more of this valuable resource.

Solar power plants, while contributing less than 1% of our electricity, use more water than thermal plants to wash the panels and for cooling of Concentrated Solar Power (CSP).

Almost all thermal power plants require about the same amount of water to cool a megawatt using conventional cooling methods.

Nuclear plant water usage:

There is a great deal of misinformation surrounding nuclear plant water usage often propagated by opponents of nuclear power. Water is recirculated for cooling of the power plant and it is consumed by the plant as well. Here’s a look at the facts:

The power block in a steam-cycle plant, which actually produces the power, will consume between 50,000 to 100,000 gallons per day depending on the design and operations.

The workers at the plant will consume 500,000 to 700,000 gallons for day for toilets, cooking, washing and other general industrial usage.

AEHI’s design will use a hybrid cooling system that will control consumption depending on water availability to less than one million gallons per day or 1000 acre-feet per year (140 acres irrigated) for the steam cycle and plant usage (listed above) if required due to water shortage. This minimum consumptive mode is known as dry cooling.

Depending on the reactor’s total power and the cooling system design, the plant can recirculate up to 20 to 25 million gallons per day for cooling. In this cooling system, water is pumped from the water source (river) to fill ponds near the power plant. It is then circulated from one pond into the plant for cooling, afterwards the water is returned to another pond to cool before being sent back to the first pond to use again. These ponds will be filled when water flow in the river is high.

Many older nuclear plants use high water consumptive cooling up to 90% of the recirculated water (such as cooling towers which are spray evaporative cooling) and were built where water was abundant from large rivers and lakes at these locations.

Source: 2005 USGS data (most recent available data)

Conclusion:

The U.S. has water for almost every use including irrigating lawns, golf courses and ball parks while using the least amount of water to produce arguably one of our most important products for the success of our economy — reliable baseload electricity.

In most of Idaho, as in the rest of the U.S., without electricity, the economy would be devastated. So, it would seem water for power production should be a very high priority especially given the amount of electricity returned from large thermal plants. Specifically, less than 1% of the water leaving Idaho would cool a large dual unit nuclear power plant producing enough reliable power to address all foreseeable growth while stabilizing increasing power costs.

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This article was very informative. I was among those that believed water consumption to cool a reactor was considerably higher. This information gives me a good deal more peace of mind about this aspect of nuclear energy, but I also consider the disposal of nuclear waste to be a really, frightening factor. What is the current policy concerning disposal of the radioactive waste?